It’s a scene straight out of a movie — but in this case, it’s nothing less than a pivotal moment in a real-life Hollywood legend’s life. Clad in a show-stopping velvet dress and fur stole, a young Marilyn Monroe glides across the floor of the Club Del Mar in Santa Monica, Calif., in January 1952. The starlet is there to pick up an award, the “Henrietta” for Best Young Box Office Personality from the Hollywood Foreign Press Association (the organization that bestows the Golden Globes).

The blonde bombshell captivates the room. She’s single, after all, and few men at the party that night fail to notice her. But in more ways than one, and to a degree that no one present can possibly imagine or foresee, the 25-year-old Marilyn’s life is about to change, and change utterly. Just a month and a half down the road, in March 1952, she will go on her first date with a professional baseball player named Joe DiMaggio. They will wed in 1954 — although the seemingly storybook marriage will last a mere nine months, before Monroe files for divorce on the grounds of “mental cruelty.”

Beyond the upheavals in her personal life, the actress’ career is about to truly take off: by the end of the year she will perform in her first starring role, alongside Richard Widmark in the thriller, Don’t Bother to Knock, while in 1953 alone she’ll star in three major movies — the noir-tinged Niagara and the romantic comedies Gentlemen Prefer Blondes and How to Marry a Millionaire. Each title will be a bigger box-office hit than the one before.

Here, six decades after that night at the Club Del Mar, LIFE.com offers a gallery of pictures, none of which ran in LIFE magazine, by photographer Loomis Dean, who captured Marilyn on the cusp of superstardom — and in the midst of what might well have been the last genuinely carefree time in the life of a young woman who would endure more and more pain, controversy and heartache as the 1950s rolled on.